BlinkGCPlugin: Fix base class trace call detection in traceImpl().

tools/clang/blink_gc_plugin/tests/traceimpl_error.h

Index: tools/clang/blink_gc_plugin/tests/traceimpl_error.h
diff --git a/tools/clang/blink_gc_plugin/tests/traceimpl_error.h b/tools/clang/blink_gc_plugin/tests/traceimpl_error.h
index 725c61c4ad325126472a1bd01a39089f9a0ee055..5a883b4e56261467156cab1c1520e224eb9d5398 100644
--- a/tools/clang/blink_gc_plugin/tests/traceimpl_error.h
+++ b/tools/clang/blink_gc_plugin/tests/traceimpl_error.h
@@ -28,7 +28,6 @@ class TraceImplInlinedWithUntracedMember
   Member<X> x_;
 };
 
-
 class TraceImplExternWithUntracedMember
     : public GarbageCollected<TraceImplExternWithUntracedMember> {
  public:
@@ -41,6 +40,29 @@ class TraceImplExternWithUntracedMember
   Member<X> x_;
 };
 
+class Base : public GarbageCollected<Base> {
+ public:
+  virtual void trace(Visitor*) {}
+};
+
+class TraceImplInlineWithUntracedBase : public Base {
+ public:
+  void trace(Visitor* visitor) override { traceImpl(visitor); }
+
+  template <typename VisitorDispatcher>
+  void traceImpl(VisitorDispatcher visitor) {
+    // Empty; should get complaints from the plugin for untraced Base.
+  }
+};
+
+class TraceImplExternWithUntracedBase : public Base {
+ public:
+  void trace(Visitor*) override;
+
+  template <typename VisitorDispatcher>
+  void traceImpl(VisitorDispatcher visitor);
+};
+
 }
 
 #endif  // TRACEIMPL_ERROR_H_